1. Field of the Invention
The present invention relates generally to computer systems. More particularly, the present invention relates to a method and apparatus for archiving de-duplicated data maintained by an intelligent backup appliance.
2. Description of the Related Art
Computer systems typically include many client computers coupled to a network. For data protection, such computer systems can include one or more backup appliances for backing up data stored on the client computers. A modern backup appliance can store much of the backup data in a de-duplicated state. With de-duplication, common data is stored only once. Backup images include unique data and references to the common de-duplicated data.
In some cases, the backup data maintained by a backup appliance is archived to archival storage (e.g., for off-site storage). Exemplary archive storage includes tape storage. Presently, to make an archive of the backup data, a backup appliance reassembles each backup image by using the references therein to combine the unique data and the common data. A complete copy of each backup image is then stored on archive storage media. Since an entire copy of each backup image is archived, a large amount of common data is duplicated across the archive storage media. As the number of backup images to be archived increases, the amount of duplicate data that is being stored also increases. This redundant copying of common data results in a large amount of wasted space on the archive storage media, requires more archive storage media than necessary, and requires more time to perform the archive process than necessary.